The present invention relates to a device for charging batteries and, more particularly, to a device for charging batteries that also serves as an AC adapter to power a normally battery powered appliance, such as, for example, a video camera.
The use of such battery charger/AC adapters for small portable electrical appliances is well known. Japanese Laid-open Utility Model Publication No. 1-61839 discloses a battery charging device that can be adapted for connection to an electrical device by moving a lever in the device from a battery charging position to a power supply position. As disclosed in this publication, overcurrent protection for the device and its attached small appliance is provided solely by an overcurrent fuse. To return this device to service following an overcurrent condition, it must be opened and the fuse must be replaced. Another inconvenience associated with this device is that an additional accessory adapter cord is needed to use the device as a power source for an electrical appliance. The internal construction of this device is also complicated by the adapter lever and its associated internal switching.
Some battery chargers can be connected to their appliance to serve as an AC adapter. Such arrangements require a cable between the battery charger and the appliance, and an adapter at the appliance to mate the cable with the normal battery retainer and connector. The requirement for a cable is inconvenient, since such cables are easily lost. In addition, the need for a special adapter tends to increase the cost of manufacture of the system.